Videoconferencing is a technique that enables people in different places to implement “real-time, visual and interactive” multimedia communication through a transmission medium. It can send a variety of information, such as a static/dynamic image of a person, a voice, a text, a picture to terminal devices of respective users by means of various existing electrical communication transmission media, such that users geographically dispersed can come together and exchange information by variety of ways such as a graph and a voice, through which the users can better understand the content of the exchanged information and thus seem to be having a conference in a same venue.
With the rapid development of technology, a videoconference terminal tends to have high audio/video definition and to be VoBB-enabled. In order to meet new business requirement of a user, the videoconference terminal tends to have increasingly complex functions, and besides the most basic videoconferencing business function, the videoconference terminal is required to have functions such as supporting transmission of document description or document presentation, i.e. a function of supporting double stream transmission. Data for the double stream transmission includes: main-stream data and other audio/video stream data other than the main-stream data, for example, a presented document on the screen of a computer, audio/video stream data on a storage device, etc.
Currently, in order to meet the new business requirement of the user, the double stream function is implemented through connection of an external device, secondary-stream data of the external device is sent to the videoconference terminal through logic switching, and then the secondary-stream data is collected and coded by the videoconference terminal. The prior art has following disadvantages: there are too many audio/video interfaces in the videoconference terminal, such that not only an aesthetic appearance of a product and the strength of a structural member are affected, but also users need to have a professional training so as to know how to operate it; for voice extension input and Video Graphics Array (VGA) video output of a computer, a very long audio/video cable is required, such that the wiring of the conference room is not convenient, and the quality of signal is affected.